AMDAbsorption Measure DistributionEvidence for Thermal Instability?

By

Tomer Holczer

Cambridge, MA July 2007

Outline

• Interesting Questions about AGN outflows

• Absorption Measure Distribution analysis – The method

• Results

• Thermal Instability?

Some Interesting Questions

• Where is the wind?

How close is it to the engine?

• Are there several absorbing components or

a continuous distribution?

• Is the absorber in pressure equilibrium?

• Do thermal instabilities play a role?

Fig 1 : NGC 3783 flux –

absorption lines from all charge states

From neutral to H-like (5 orders in )

The Data

Outflow Model : Method• Determine continuum

• Identify absorption lines; determine outflow and broadening velocity

• Obtain column densities from data of each individual ion

by fitting all its lines

• Reconstruct the Absorption Measure Distribution (as a function of )

Fig 2 : IRAS 13349+2438 line profile of Fe+16 resonance

at 15 Å (in black) and model in red. Fitting the

broadening (width) and outflow (shift) velocity.

)(2Rn

L

H

=

Absorption Measure Distribution , A New Method(analogous to emission measure distribution)

• Improvement on multi-component models

• AMD – Absorption Measure Distribution –

is the gas column-density (NH) distribution in

ionization parameter ξ : AMD

€

N ion = Az f ion (ξ )∂NH (ξ )

∂ξ

⎛ ⎝ ⎜

⎞ ⎠ ⎟∫ dξ

Measuring Nion from HETG data

Fig 3 : NGC 3783 (left panel), IRAS 13349+2438 (middle panel), and MCG -6-30-15 (right

panel). spectra in black, model in red.

Iron ion fractional abundances

0

0.1

0.2

0.3

0.4

0.5

0.6

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Ionization Parameter log (\xi) [erg cm s -1]

Fractional Abundance

Fe+16

Fe+24

Fe+5 NGC 3783

Fig 4: Iron ion’s relative abundances for NGC 3783 using XSTAR (Kallman & Krolik 1995)

Fig 5 : AMD of IRAS 13349+2438.

The lower panel is the integrated

column density.

For IRAS 13349+2438 NH ~ 1022 cm-2 .

d

NfAN Hionzion ∫ ⎟⎟

⎠

⎞⎜⎜⎝

⎛∂

∂=

)()(

Abundance Ratios Compared to Sun

Fig 6 : AMD of NGC 7469.

(Blustin et al. 2007).

NH ~ 3 1021 cm-2.

Fig 7 : AMD of NGC 3783.

The cyan bins in NGC 3783

are the Krongold et al.

model (with a bin width) and

the green bins Netzer et al.

model .

NH ~ 4 1022 cm-2.

Photo-ionized Plasma Models for NGC 3783

red squares represent the observed gap

ION (Netzer et al. 2003)

XSTAR (Used by Holczer et al. 2007)

CLOUDY (Krongold et al. 2003)

TITAN (Goncalves et

al. 2006)

Cooling Curves

Cooling rates at different values of ξ/T (Krolik et al. 1981))

Conclusions• All outflows in the AGN’s we’ve checked are missing gas

at logT ~ 4.5 - 5 K

• We believe this is evidence for thermal instability in this

region

• Observed unstable region is not produced exactly by

codes

• Moreover, there are discrepancies between the different

models

THE END

Fig 6 : Preliminary AMD of

MCG -6-30-15. MCG -6-30-

15 have total column

density around 7 1021 cm-2.

2±0.5

1.2±0.3

1.7±0.7

0.7±0.2

3.7±2

MCG -6-15-30 (Az/AFe)/

(Az/AFe)O

0.7 ±0.78.71 ±1.41Carbon

4.3±2.68.38 ±5.620.6±0.52.14±0.38Nitrogen

1.9±0.42.3±0.811±91.15±0.17Silicon

1.0 ±0.3 6±5.50.49±0.08Sulfur

1.5 ±0.51.4±0.51.0±0.91.20±0.29Magnesium

1.9 ±0.630±201.20±0.29Sodium

1.4±0.51.3 ±0.83.0±1.32.64±0.44Neon

1.0±0.21.3 ±0.51.3±0.52.64±16.22

Oxygen

NGC 3783 (Az/AFe)/

(Az/AFe)O

IRAS 13349+2438 (Az/AFe)/

(Az/AFe)O

NGC 7469 (Az/AFe)/

(Az/AFe)O

Sun Ratios (Az/AFe)O

from Asplund et al. 2005

Element